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UCC2813-1: UCC2813-1

lev nemets1
Intellectual 475 points
Part Number: UCC2813-1

Tool/software:

Hello

Could you, please, explain how overcurrent protection works. The overcurrent current comparator has a 1.5V threshold. But how voltage on CS pin can reach this threshold if current limiting circuit will limit it to 1V? I tried to simulate this condition using your spice model for UCCx813-1 in 2 MOSFET forward converter.  To simulate a severe fault, I shorted transformer primary winding (3.5mH) with 10uH inductance. Simulation shows that CS voltage does exceed 1.5V threshold but overcurrent comparator inside your model (X4 COMPARCS ) does not work properly. Could you, please, explain this results.

Regards

Lev

  • 0
    TI__Guru 73825 points

    Hi,

    The 1.5V threshold needs to be triggered with very sharp rising edge, typically from 0 to 1.5V needs to be < 50ns. If the rising time longer then 1.0V threshold will turn off OUT pin pulse and 1.5V trigger is not made.